Environmental pollutants such as microplastics have become a major concern over the last few decades. We investigated the presence, characteristics, and potential health risks of microplastic dust ingestion. The plastic load of 88 to 605 microplastics per 30 g dry dust with a dominance of black and yellow granule microplastics ranging in size from 250 to 500 μm was determined in 10 street dust samples using a binocular microscope. Fluorescence microscopy was found to be ineffective for detecting and counting plastic debris. Scanning electron microscopy, however, was useful for accurate detection of microplastic particles of different sizes, colors, and shapes (e.g., fiber, spherule, hexagonal, irregular polyhedron). Trace amounts of Al, Na, Ca, Mg, and Si, detected using energy dispersive X-ray spectroscopy, revealed additives of plastic polymers or adsorbed debris on microplastic surfaces. As a first step to estimate the adverse health effects of microplastics in street dust, the frequency of microplastic ingestion per day/year via ingestion of street dust was calculated. Considering exposure during outdoor activities and workspaces with high abundant microplastics as acute exposure, a mean of 3223 and 1063 microplastic particles per year is ingested by children and adults, respectively. Consequently, street dust is a potentially important source of microplastic contamination in the urban environment and control measures are required.

Different types of manganese ore raw materials were prepared for use as catalysts, and the effects of different manganese ore raw materials and calcination temperature on the NO conversion were analyzed. The catalysts were characterized by XRF, XRD, BET, XPS, H₂-TPR, NH₃-TPD, and SEM techniques. The results showed that the NO conversion of calcined manganese ore with a Mn:Fe:Al:Si ratio of 1.51:1.26:0.34:1 at 450 °C reached 80% at 120 °C and 98% at 180~240 °C. The suitable proportions and better dispersibility of active ingredients, larger BET surface area, good reductibility, a lot of acid sites, contents of Mn⁴⁺ and Fe³⁺, and surface-adsorbed oxygen played important roles in improving the NO conversion.

Microbial fuel cells (MFCs) are emerging technology for wastewater treatment by chemical oxygen demand (COD) reduction and simultaneous bioelectricity production. Fabrication of an effective proton exchange membrane (PEM) is a vital component for MFC performance. In this work, green chitosan-based (CS) PEMs were fabricated with graphene oxide (GO) as filler material (CS-GO) and cross-linked with phosphoric acid (CS-GO-P(24)) or sulfuric acid (CS-GO-S(24)) to determine their effect on PEM properties. Interrogation of the physicochemical, thermal, and mechanical properties of the cross-linked CS-GO PEMs demonstrated that ionic cross-linking based on the incorporation of PO₄ ³⁻ groups in the CS-GO mixed-matrix composites, when compared with sulfuric acid cross-linking commonly used in proton exchange membrane fuel cell (PEMFC) studies, generated additional density of ionic cluster domains, rendered enhanced sorption properties, and augmented the thermal and mechanical stability of the composite structure. Consequently, bioelectricity performance analysis in MFC application showed that CS-GO-P(24) membrane produced 135% higher power density than the CS-GO-S(24) MFC system. Simultaneously, 89.52% COD removal of primary clarifier municipal wastewater was achieved in the MFC operated with the CS-GO-P(24) membrane.

Like other developing countries, Pakistan is also facing changes in temperature per decade and other climatic abnormalities like droughts and torrential rains. In order to assess and identify the extent of temperature change over Pakistan, the whole Pakistan was divided into five climatic zones ranging from very cold to hot and dry climates. Similarly, seasons in Pakistan are defined on the basis of monsoon variability as winter, pre-monsoon, monsoon, and post-monsoon. This study primarily focuses on the comparison of surface temperature observations from Pakistan Meteorological Department (PMD) network with PRECIS (Providing Regional Climates for Impacts Studies) model simulations. Results indicate that PRECIS underestimates the temperature in Northern Pakistan and during the winter season. However, there exists a fair agreement between PRECIS output and observed datasets in the lower plain and hot areas of the country. An absolute increase of 0.07 °C is observed in the mean temperature over Pakistan during the time period of 1951–2010. Especially, the increase is more significant (0.7 °C) during the last 14 years (1997–2010). Moreover, SCIAMACHY observations were used to explore the evolution of atmospheric CO₂ levels in comparison to temperature over Pakistan. CO₂ levels have shown an increasing trend during the first decade of the twenty-first century.

Discharge of organic waste results in high nutrient pollution of the water bodies which is a major menace to the environment. A high quantity of nutrients such as ammonia causes a reduction in the dissolved oxygen level and induces algal growth in the water bodies. Water quality models have been the tools to evaluate the rate at which streams can disperse the pollutants they receive. Many water quality models are flawed either because of their inadequacy to completely simulate the advection component of the pollutant transport, or because of the limited application of the models, due to inaccurate estimation of model parameters. The hybrid cell in series (HCIS) developed by Ghosh et al. (2004) has been able to overcome such difficulties associated with the mixing cell-based models. Thus, the current study focuses on developing an analytical solution for the pollutant transport of the ammonia concentration through the plug flow, the first and second well-mixed cells of the HCIS model. The HCIS model coupled with the first order kinetic equation for ammonia nutrient was developed to simulate the ammonia pollutant concentration in the water column. The ammonia concentration at various points along the river system was assessed by considering the effects of the transformation of ammonia to nitrite, the uptake of ammonia by the algae, the respiration rate of the algae and the input of benthic source to the ammonia concentration in the water column. The proposed model was tested using synthetic data, and the HCIS-NH₃ model simulations for spatial and temporal variation of ammonia pollutant transport were analysed. The simulated results of the HCIS-NH₃ model agreed with the Fickian-based advection-dispersion equation (ADE) for simulating ammonia concentration solved using an explicit finite difference scheme. The HCIS-NH₃ model also showed a good agreement with the observed data from the Umgeni River, except during rainy periods.

The nanofiltration (NF) membrane fouling characteristics and cleaning strategies were investigated through a laboratory-scale NF fouling test treating membrane bioreactor (MBR) effluent and MBR-granular activated carbon (GAC) effluent of an antibiotic production wastewater by DK and NF90 membranes, respectively. Results showed that organic fouling is the main NF membrane fouling for treating both the MBR effluent and MBR-GAC effluent. Soluble microbial by-product (SMP)-like and aromatic protein-like substances were the dominant components in the foulants, whereas humic-like substances had little contribution to the NF fouling. The fouling of DK was more severe than that of NF90. However, foulants respond by UV₂₅₄ were more easily to foul NF90 membrane. It could get satisfactory effect using combined cleaning of acid (HCl, pH 2.0∼2.5) and alkali (NaOH + 0.3 wt% NaDS, pH 10.0∼10.5). The favorable cleaning strategy is “acid + alkali” for treating MBR-GAC effluent, while it is “alkali + acid” for treating MBR effluent.

The Gironde estuary (S-W France) is one of the largest European macrotidal estuaries. In the tidal Garonne River, its main tributary, episodes of low (<5 mg L⁻¹) to hypoxic (<2 mg L⁻¹) dissolved oxygen (DO) concentrations have been occasionally recorded close to Bordeaux, about 100 km from the mouth. Projected long-term environmental changes (increase in temperature and population, decrease in river discharge) suggest the establishment of summer chronic oxygen deficiency in the tidal Garonne River in the next decades. Assessing and managing the risk of hypoxia on such a large, hyper-turbid fluvio-estuarine system is complex, due to the different forcing factors (temperature, river discharge, turbidity, urban wastes) acting over a wide range of temporal and spatial scales. In this context, we show the interest of a real-time, high-frequency monitoring of the water quality, the MAGEST network, which continuously records since 2005 temperature, salinity, turbidity, and dissolved oxygen in surface waters in Bordeaux. Through the analysis of the 10-year DO records, we demonstrate the interest of a high-frequency, long-term database to better document DO variability and to define the controlling factors of DO concentrations. This real-time monitoring is also of great interest for the development of manager’s oriented tools and the follow-up of DO objectives in the tidal Garonne River.

Chromite ore processing residue (COPR) is generated by the roasting of chromite ores for the extraction of chromium. Leaching of carcinogenic hexavalent chromium (Cr(VI)) from COPR dumpsites and contamination of groundwater is a key environmental risk. The objective of the study was to evaluate Cr(VI) contamination in groundwater in the vicinity of three COPR disposal sites in Uttar Pradesh, India, in the pre-monsoon and monsoon seasons. Groundwater samples (n = 57 pre-monsoon, n = 70 monsoon) were taken in 2014 and analyzed for Cr(VI) and relevant hydrochemical parameters. The site-specific ranges of Cr(VI) concentrations in groundwater were <0.005 to 34.8 mg L⁻¹ (Rania), <0.005 to 115 mg L⁻¹ (Chhiwali), and <0.005 to 2.0 mg L⁻¹ (Godhrauli). Maximum levels of Cr(VI) were found close to the COPR dumpsites and significantly exceeded safe drinking water limits (0.05 mg L⁻¹). No significant dependence of Cr(VI) concentration on monsoons was observed.

Psychotropic substances (PSs) are known to affect air and waters, while scarce attention has been paid to their occurrence in settled dusts although they can reach important concentrations there; moreover, no procedures have been developed for this specific purpose. In this study, a list of PSs (i.e., nicotine, cotinine, caffeine, cocaine, cannabinol, Δ⁹-tetrahydrocannabinol, cannabidiol, amphetamine, heroin, and methadone) were characterized in dusts from Rome and Fiumicino international airport, Italy, and from Ouargla city, Algeria. The analytical procedure, based on ultra-sonic bath extraction, silica column chromatography, and GC-MSD analysis, provided good recovery, uncertainty, sensitivity, and lack of interferences for all substances except amphetamine. In NIST SRM-2585 house dust, nicotine, cotinine, caffeine, cocaine, and cannabinol accounted for ~5.95, 0.87, 4.17, 7.0, and 2.2 μg/g, respectively; on the other hand, methadone, tetrahydrocannabinol, cannabidiol, and heroin (all <0.025 μg/g) were below the detection limit of the method. Two sites at the Fiumicino airport were affected by different loads of PSs (e.g., 0.76 and 2.80 ng/m² of cocaine). In Ouargla, where dust was collected in a primary school and a dwelling, nicotine ranged from ~60 ± 50 to ~86 ± 89 ng/m², cocaine was absent, and cannabinoids (0.35 ± 0.43 ng/m² as total) were found only in the home. In Rome, nicotine, caffeine, cocaine, and cannabinol reached ca. 700, 1470, 0.82, and 2.4 ng/m², respectively, in a smokers’ home, but they were ca. 1300, 25,000, 670, and 1700 ng/m² in a non-smoker home. In conclusion, all dusts revealed the presence of illicit PSs. Further studies are necessary to understand the links between the PS amounts in airborne particulates and in dusts, as well as the PS origin and fate in interiors.

Nowadays, public concerns regarding deleterious effect of lead (Pb) is on rise due to its abundance and toxic effect on plants and other living organisms. In plants, it has no noticeable biological importance but can cause various morphological, physiological, and biochemical malfunctions. To evaluate the remediating potential of plant-derived smoke (Cymbopogon jwarancusa), a pot culture experiment was designed to investigate the physiological, biochemical, metabolic, and antioxidant parameters of roots in lead (0 (control), 500, 1000, and 1500 ppm)-contaminated soil. Under dark condition, seeds were primed in smoke solution with two dilutions (1:500 and 1:1000) for 24 h. With an increasing concentration of Pb stress, fresh and dry weight and total nitrogen and protein contents decreased significantly while an increase was observed in smoke-treated seed. With increasing Pb stress level, metabolites (i.e., proline, total soluble sugar, total soluble protein, glycine betaine), and antioxidants (i.e., superoxide dismutase, peroxidase, catalase, ascorbate peroxidase, malonyldialdehyde, and H₂O₂), contents of roots were increased in non-treated (without smoke treatment) samples, whereas comparatively, a low level of alteration in aforementioned metabolites and antioxidative parameters was observed in the seeds treated with smoke solution. These results suggest a positive role of smoke in alleviating lead-induced changes in roots of two cultivated cultivars of rice grown in Pb-contaminated soil.